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/* $OpenBSD: copy.c,v 1.4 2022/12/26 19:16:02 jmc Exp $ */
/*
* Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <err.h>
#include <fcntl.h>
#include <unistd.h>
#include "extern.h"
#define _MAXBSIZE (64 * 1024)
/*
* Return true if all bytes in buffer are zero.
* A buffer of zero length is also considered a zero buffer.
*/
static int
iszero(const void *b, size_t len)
{
const unsigned char *c = b;
for (; len > 0; len--) {
if (*c++ != '\0')
return 0;
}
return 1;
}
static int
copy_internal(int fromfd, int tofd)
{
char buf[_MAXBSIZE];
ssize_t r, w;
while ((r = read(fromfd, buf, sizeof(buf))) > 0) {
if (iszero(buf, sizeof(buf))) {
if (lseek(tofd, r, SEEK_CUR) == -1)
return -1;
} else {
w = write(tofd, buf, r);
if (r != w || w == -1)
return -1;
}
}
if (r == -1)
return -1;
if (ftruncate(tofd, lseek(tofd, 0, SEEK_CUR)) == -1)
return -1;
return 0;
}
void
copy_file(int rootfd, const char *basedir, const struct flist *f)
{
int fromfd, tofd, dfd;
dfd = openat(rootfd, basedir, O_RDONLY | O_DIRECTORY);
if (dfd == -1)
err(ERR_FILE_IO, "%s: openat", basedir);
fromfd = openat(dfd, f->path, O_RDONLY | O_NOFOLLOW);
if (fromfd == -1)
err(ERR_FILE_IO, "%s/%s: openat", basedir, f->path);
close(dfd);
tofd = openat(rootfd, f->path,
O_WRONLY | O_NOFOLLOW | O_TRUNC | O_CREAT | O_EXCL,
0600);
if (tofd == -1)
err(ERR_FILE_IO, "%s: openat", f->path);
if (copy_internal(fromfd, tofd) == -1)
err(ERR_FILE_IO, "%s: copy file", f->path);
close(fromfd);
close(tofd);
}
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